[SPARK-19970][SQL][BRANCH-1.6] Table owner should be USER instead of PRINCIPAL in kerberized clusters

[dongjoon-hyun]

What changes were proposed in this pull request?

In the kerberized hadoop cluster, when Spark creates tables, the owner of tables are filled with PRINCIPAL strings instead of USER names. This is inconsistent with Hive and causes problems when using ROLE in Hive. We had better to fix this. For Apache Spark 1.6, it happens only with CREATE TABLE ... AS SELECT (CTAS) statement.

BEFORE

scala> sql("create table t_ctas as select 1").show
scala> sql("desc formatted t_ctas").show(false)
...
|Owner:                      |spark@EXAMPLE.COM                                         |       |

AFTER

scala> sql("create table t_ctas as select 1").show
scala> sql("desc formatted t_ctas").show(false)
...
|Owner:                      |spark                                         |       |

How was this patch tested?

Manually do create table and desc formatted because this happens in Kerberized clusters.

[SparkQA]

Test build #74907 has finished for PR 17366 at commit 6c726dd.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dongjoon-hyun]

I'm closing this for branch-1.6 according to the advice.
Thank you!